The shootings occurred Oct. 16 through Oct. 18, then stopped until Oct. 27.

Casteel has described himself online as a geologist with experience in environmental cleanup. His Twitter feed is deeply critical of President Barack Obama.

The Saginaw News is reporting that Casteel has no prior criminal record. Casteel's mother Lana Hunt has told the Detroit Free Press that she's worried he might be mentally ill but refuses to see a doctor.